Updated alert tag helper example

test/Volo.Abp.AspNetCore.Mvc.UI.Bootstrap.Demo/Pages/Components/Alerts.cshtml

@@ -71,7 +71,7 @@
     <div class="demo-area">
 
         <abp-alert alert-type="Primary">
-            <h4 abp-alert-header>Header</h4>
+            <h4>Header</h4>
             I'm an abp alert!
         </abp-alert>
 
@@ -79,7 +79,7 @@
     <div class="code-area">
         <pre>
 &lt;abp-alert alert-type=&quot;Primary&quot;&gt;
-    &lt;h4 abp-alert-header&gt;Header&lt;/h4&gt;
+    &lt;h4&gt;Header&lt;/h4&gt;
     I&#39;m an abp alert!
 &lt;/abp-alert&gt;
 </pre>